Popping bypass switches - even with pulldown R's

[Jim Jones]

Hey guys,

Now that summer is coming to an end I'm starting to get back into amps and effects again.  I recently built another Rangemaster-type pedal and was comparing it with my first homebrew one and noticed a huge difference - in the switch popping!!!

My "original" pops incredibly loudly.  I opened it up, noticed that there were no pulldown resistors, so I put in some 1M's and tried it out.  The bugger popped just as loudly as before!  I had used some older polyester caps for input and output, so I changed those (wondering if they were leaky) to some ceramics...same thing, aaarggghhhh!!!

I tried a Miyama switch and then swapped it out for a British-made DPDT - still popping!  Would you think my bypass switches are the culprit?  Are Carlings and the Taiwanese blue jobbies less susceptible to pops?

I tried both RM's with two different amps and that's where things get even weirder - both pedals popped louder with one amp than the other.  And both amps have the exact same input section!!!  Bizarre, alright...any insight would be much appreciated!

Thanks!

Jim

[R.G.]

check the pedals with a voltmeter. IF theyre is DC on the outputs of the pedals, no amount of pulldown resistors will prevent popping. A bad output or input capacitor will do what you're describing.

R.G.

[Jim Jones]

Hey R.G.,

I am getting very tiny (fraction of a mA) readings on some of the caps I measured...I assume this is enough to be the cause...

Jim

[R.G.]

Even 1uA will cause popping.  When I designed the Millenium Bypass, I had to use the reverse leakage of a signal diode (about 10-15 nano-amperes!) as a bias source to keep the popping down to negligible.

R.G.